The present invention relates to an image dye-forming coupler which also functions as a filter dye or a masking coupler. In particular, it relates to an arylidene pyrazolone image dye-forming coupler.
A color photographic material based on the subtractive color process system conventionally includes at least one blue-sensitive silver halide emulsion layer containing at least one yellow image dye-forming coupler, at least one green-sensitive silver halide emulsion layer containing at least one magenta image dye-forming coupler and at least one red-sensitive silver halide emulsion layer containing at least one cyan image dye-forming coupler. It is well known to employ filter dyes or layers in such multilayer color photographic materials to prevent exposure of underlying light-sensitive silver halide emulsion layers to light having a wavelength which is absorbed undesirably by the underlying light-sensitive emulsion layer. This problem with undesired absorption by the silver halide emulsion layers is especially significant with respect to blue light since the natural silver halide sensitivity is to blue light, regardless of whether the silver halides are sensitized to other colors such as green or red.
A yellow filter dye, therefore, typically is incorporated in the photographic material above the green- and/or red-sensitive emulsion layers in order to absorb the undesired blue light during exposure of the photographic material. To avoid the unwanted presence of a high blue D.sub.min after processing, however, the yellow filter dyes should be capable of removal and/or decolorization during processing of the photographic material.
Conventionally, filter dyes and image dye-forming couplers are separate compounds. This results in the disadvantage of requiring the production of numerous different compounds and increases the manufacturing problems associated with incorporating a large number of compounds and/or layers in a color photographic material.
U.S. Pat. Nos. 2,688,538, 2,688,540 and 2,688,541 and United Kingdom Patent Specification No. 968,461 disclose a styryl dye formed from a pyrazolone magenta dye-forming coupler parent which includes a substituted or unsubstituted amino group in a position on the benzene ring para to the methylene group. The amino group, however, prevents these dyes from undergoing rapid decolorization during processing.
U.S. Pat. No. 4,311,787 discloses a class of arylidene pyrazolone compounds which act only as classic filter dyes rather than as filter dye/image dye-forming couplers. These filter dyes do not function as image dye-forming couplers because, among other reasons, they wash out of the photographic film into the developer since they do not include ballast groups.
It is also well known to utilize a masking coupler in photographic materials for color correction of the undesirable side-absorption tendencies of the cyan, magenta and yellow dye images. For example, the conventional masking technique for use with a magenta dye is to employ a colored magenta dye forming coupler, i.e., a masking coupler, which is colored (yellow) so that it has an absorption in the unwanted blue region.